REFERENCE: N Engl J Med 355: 1539-50 A new test for TB, trialled in Peru, has proved more powerful and yet faster and cheaper than alternatives, making it especially suitable for use in resource-limited settings where tuberculosis is becoming more rampant, partly through the world-wide advance of HIV. David Moore and his colleagues have published results in the New England Journal of Medicine of a massive investigation conducted in Lima with nearly 4 000 samples of the sputum test called: Microscopic-Observation Drug-Susceptibility (MODS) Assay. Their findings promise not only to improve diagnosis and save lives in developing countries and other settings with limited health-care resources, but also out-perform costly gold-standard technology-intensive TB diagnosis methods currently used where cash is not a problem. The MODS test, David Moore told Peter Goodwin during a visit to Peru, gives sensitive and specific diagnosis in as little as seven days, and concurrently yields drug susceptibility data which helps combat multi-drug resistant TB.